Thermostat wont open, help!
Hey all, brand new to the forum, I have a Ford F-150 4x4 shortbed with a 302 in it. I have recently tried putting a new thermostat in, and it wont open up at 180f. I tested both the thermostats I have, and they tested fine. But when I put it in the truck it wont open up, all the coolant in the radiator and hoses stays cold and the block gets hot, and I have had the block up over 180f. Then when I take it back out and let it free flow, it works fine, accept obviously I don't have any heat and I cant get it up to operating temp. Everything flows fine , heater works fine but I cant put the stat in. Someone told me that it could be some sort of vapor lock , like air getting in somewhere and making a pocket behind the stat somewhere and not letting the stat open. Anyone have any insight on this, Im at a dead end. Thanks